adc08200 8-bit,20 msps to 200 msps, low power a/d ...just 1.05 mw per mhz of clock frequency, or 210...

ADC08200

www.ti.com SNAS136M –APRIL 2001–REVISED MARCH 2013

ADC08200 8-Bit, 20 Msps to 200 Msps, Low Power A/D Converter with Internal Sample-and-Hold

Check for Samples: ADC08200

1FEATURES DESCRIPTIONThe ADC08200 is a low-power, 8-bit, monolithic

2• Single-Ended Inputanalog-to-digital converter with an on-chip track-and-

• Internal Sample-and-Hold Function hold circuit. Optimized for low cost, low power, small• Low Voltage (Single +3V) Operation size and ease of use, this product operates at

conversion rates up to 230 Msps while consuming• Small Packagejust 1.05 mW per MHz of clock frequency, or 210 mW• Power-Down Feature at 200 Msps. Raising the PD pin puts the ADC08200into a Power Down mode where it consumes about 1

KEY SPECIFICATIONS mW.• Resolution 8 Bits The unique architecture achieves 7.3 Effective Bits• Maximum sampling frequency 200 Msps (min) with 50 MHz input frequency. The ADC08200 is

resistant to latch-up and the outputs are short-circuit• DNL ±0.4 LSB (typ)proof. The top and bottom of the ADC08200's• ENOB (fIN = 50 MHz) 7.3 bits (typ) reference ladder are available for connections,

• THD (fIN = 50 MHz) 61 dB (typ) enabling a wide range of input possibilities. Thedigital outputs are TTL/CMOS compatible with a• Power Consumptionseparate output power supply pin to support– Operating 1.05 mW/Msps (typ)interfacing with 3V or 2.5V logic. The digital inputs

– Power Down 1 mW (typ) (CLK and PD) are TTL/CMOS compatible. The outputdata format is straight binary.

APPLICATIONSThe ADC08200 is offered in a 24-lead TSSOP

• Flat Panel Displays package and, while specified over the industrialtemperature range of −40°C to +85°C, it will function• Projection Systemsover the to −40°C to +105°C temperature range.• Set-Top Boxes

• Battery-Powered Instruments• Communications• Medical Imaging• Astronomy

1

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications ofTexas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date. Copyright © 2001–2013, Texas Instruments IncorporatedProducts conform to specifications per the terms of the TexasInstruments standard warranty. Production processing does notnecessarily include testing of all parameters.

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VRT

VRM

256

1

SWITCHES

CLOCKGEN

COARSE/FINECOMPARATORS

ENCODER& ERROR

CORRECTION

17

CLK

17

COARSE/FINECOMPARATORS

ENCODER& ERROR

CORRECTION

17

VA (pin 18)

AGNDVIN

8

8

OUTPUTDRIVERS

MUX

8 8DATAOUT

PD

DR VD

DR GND(pin 17)

VRB

VIN GND

ADC08200

SNAS136M –APRIL 2001–REVISED MARCH 2013 www.ti.com

Block Diagram

Pin Configuration

Figure 1. 24-Lead TSSOPSee PW Package

2 Submit Documentation Feedback Copyright © 2001–2013, Texas Instruments Incorporated

Product Folder Links: ADC08200


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VD

DGND

ADC08200


PIN DESCRIPTIONS AND EQUIVALENT CIRCUITSPin No. Symbol Equivalent Circuit Description

6 VIN Analog signal input. Conversion range is VRB to VRT.

Analog Input that is the high (top) side of the reference ladderof the ADC. Nominal range is 0.5V to VA. Voltage on VRT and3 VRT VRB inputs define the VIN conversion range. Bypass well. SeeTHE ANALOG INPUT for more information.

Mid-point of the reference ladder. This pin should be bypassed9 VRM to a quiet point in the ground plane with a 0.1 µF capacitor.

Analog Input that is the low side (bottom) of the referenceladder of the ADC. Nominal range is 0.0V to (VRT – 0.5V).

10 VRB Voltage on VRT and VRB inputs define the VIN conversionrange. Bypass well. See THE ANALOG INPUT for moreinformation.

Power Down input. When this pin is high, the converter is in23 PD the Power Down mode and the data output pins hold the last

conversion result.

CMOS/TTL compatible digital clock Input. VIN is sampled on24 CLK the rising edge of CLK input.

13 thru 16 Conversion data digital Output pins. D0 is the LSB, D7 is theand D0–D7 MSB. Valid data is output just after the rising edge of the CLK

19 thru 22 input.

7 VIN GND Reference ground for the single-ended analog input, VIN.

Positive analog supply pin. Connect to a quiet voltage sourceof +3V. VA should be bypassed with a 0.1 µF ceramic chip1, 4, 12 VA capacitor for each pin, plus one 10 µF capacitor. See POWERSUPPLY CONSIDERATIONS for more information.

Power supply for the output drivers. If connected to VA,18 VDR decouple well from VA.

17 DR GND The ground return for the output driver supply.

2, 5, 8, 11 AGND The ground return for the analog supply.

Copyright © 2001–2013, Texas Instruments Incorporated Submit Documentation Feedback 3



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ADC08200


These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foamduring storage or handling to prevent electrostatic damage to the MOS gates.

Absolute Maximum Ratings (1) (2) (3)

Supply Voltage (VA) 3.8V

Driver Supply Voltage (VDR) VA +0.3V

Voltage on Any Input or Output Pin −0.3V to VA

Reference Voltage (VRT, VRB) VA to AGND

CLK, PD Voltage Range −0.05V to(VA + 0.05V)

Input Current at Any Pin (4) ±25 mA

Package Input Current (4) ±50 mA

Power Dissipation at TA = 25°C See (5)

ESD Susceptibility (6) Human Body Model 2500V

Machine Model 200V

Soldering Temperature, Infrared,10 seconds (7) 235°C

Storage Temperature −65°C to +150°C

(1) All voltages are measured with respect to GND = AGND = DR GND = 0V, unless otherwise specified.(2) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for

which the device is functional, but do not ensure specific performance limits. For ensured specifications and test conditions, see theElectrical Characteristics. The ensured specifications apply only for the test conditions listed. Some performance characteristics maydegrade when the device is not operated under the listed test conditions.

(3) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability andspecifications.

(4) When the input voltage at any pin exceeds the power supplies (that is, less than AGND or DR GND, or greater than VA or VDR), thecurrent at that pin should be limited to 25 mA. The 50 mA maximum package input current rating limits the number of pins that cansafely exceed the power supplies with an input current of 25 mA to two.

(5) The absolute maximum junction temperature (TJmax) for this device is 150°C. The maximum allowable power dissipation is dictated byTJmax, the junction-to-ambient thermal resistance (θJA), and the ambient temperature (TA), and can be calculated using the formulaPDMAX = (TJmax − TA) / θJA. The values for maximum power dissipation listed above will be reached only when this device is operatedin a severe fault condition (e.g., when input or output pins are driven beyond the power supply voltages, or the power supply polarity isreversed). Obviously, such conditions should always be avoided.

(6) Human body model is 100 pF capacitor discharged through a 1.5 kΩ resistor. Machine model is 220 pF discharged through ZEROOhms.

(7) See AN-450, “Surface Mounting Methods and Their Effect on Product Reliability” (SNOA742).

Operating Ratings (1) (2)

Operating Temperature Range −40°C ≤ TA ≤ +105°C

Supply Voltage (VA) +2.7V to +3.6V

Driver Supply Voltage (VDR) +2.4V to VA

Ground Difference |GND - DR GND| 0V to 300 mV

Upper Reference Voltage (VRT) 0.5V to (VA −0.3V)

Lower Reference Voltage (VRB) 0V to (VRT −0.5V)

VIN Voltage Range VRB to VRT

(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions forwhich the device is functional, but do not ensure specific performance limits. For ensured specifications and test conditions, see theElectrical Characteristics. The ensured specifications apply only for the test conditions listed. Some performance characteristics maydegrade when the device is not operated under the listed test conditions.

(2) All voltages are measured with respect to GND = AGND = DR GND = 0V, unless otherwise specified.

Package Thermal Resistance

Package θJA

24-Lead TSSOP 92°C/W




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ADC08200


Converter Electrical CharacteristicsThe following specifications apply for VA = VDR = +3.0VDC, VRT = +1.9V, VRB = 0.3V, CL = 5 pF, fCLK = 200 MHz at 50% dutycycle. Boldface limits apply for TJ = TMIN to TMAX: all other limits TJ = 25°C (1) (2) (3)

UnitsSymbol Parameter Conditions Typical (4) Limits (4)(Limits)

DC ACCURACY

+1.0 +1.9 LSB (max)INL Integral Non-Linearity −0.3 −1.2 LSB (min)

DNL Differential Non-Linearity ±0.4 ±0.95 LSB (max)

Missing Codes 0 (max)

FSE Full Scale Error 36 50 mV (max)

VOFF Zero Scale Offset Error 46 60 mV (max)

ANALOG INPUT AND REFERENCE CHARACTERISTICS

VRB V (min)VIN Input Voltage 1.6 VRT V (max)

(CLK LOW) 3 pFCIN VIN Input Capacitance VIN = 0.75V +0.5 Vrms

(CLK HIGH) 4 pF

RIN RIN Input Resistance >1 MΩBW Full Power Bandwidth 500 MHz

VA V (max)VRT Top Reference Voltage 1.9

0.5 V (min)

VRT − 0.5 V (max)VRB Bottom Reference Voltage 0.3

0 V (min)

1.0 V (min)VRT - VRB Reference Voltage Delta 1.6

2.3 V (max)

120 Ω (min)RREF Reference Ladder Resistance VRT to VRB 160

200 Ω (max)

CLK, PD DIGITAL INPUT CHARACTERISTICS

VIH Logical High Input Voltage VDR = VA = 3.6V 2.0 V (min)

VIL Logical Low Input Voltage VDR = VA = 2.7V 0.8 V (max)

IIH Logical High Input Current VIH = VDR = VA = 3.6V 10 nA

IIL Logical Low Input Current VIL = 0V, VDR = VA = 2.7V −50 nA

CIN Logic Input Capacitance 3 pF

(1) The Electrical characteristics tables list ensured specifications under the listed Recommended Conditions except as otherwise modifiedor specified by the Electrical Characteristics Conditions and/or Notes. Typical specifications are estimations for room temperature onlyand are not ensured.

(2) The analog inputs are protected as shown below. Input voltage magnitudes up to VA + 300 mV or to 300 mV below GND will notdamage this device. However, errors in the A/D conversion can occur if the input goes above VDR or below GND by more than 100 mV.For example, if VA is 2.7VDC the full-scale input voltage must be ≤2.8VDC to ensure accurate conversions.

(3) To ensure accuracy, it is required that VA and VDR be well bypassed. Each supply pin must be decoupled with separate bypasscapacitors.

(4) Typical figures are at TJ = 25°C, and represent most likely parametric norms. Test limits are specifid to TI's AOQL (Average OutgoingQuality Level).




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ADC08200


Converter Electrical Characteristics (continued)The following specifications apply for VA = VDR = +3.0VDC, VRT = +1.9V, VRB = 0.3V, CL = 5 pF, fCLK = 200 MHz at 50% dutycycle. Boldface limits apply for TJ = TMIN to TMAX: all other limits TJ = 25°C (1)(2)(3)


DIGITAL OUTPUT CHARACTERISTICS

VOH High Level Output Voltage VA = VDR = 2.7V, IOH = −400 µA 2.6 2.4 V (min)

VOL Low Level Output Voltage VA = VDR = 2.7V, IOL = 1.0 mA 0.4 0.5 V (max)

DYNAMIC PERFORMANCE

fIN = 4 MHz, VIN = FS − 0.25 dB 7.5 Bits


ENOB Effective Number of Bits fIN = 50 MHz, VIN = FS − 0.25 dB 7.3 6.9 Bits (min)



fIN = 4 MHz, VIN = FS − 0.25 dB 47 dB


SINAD Signal-to-Noise & Distortion fIN = 50 MHz, VIN = FS − 0.25 dB 46 43.3 dB (min)





SNR Signal-to-Noise Ratio fIN = 50 MHz, VIN = FS − 0.25 dB 46 43.4 dB (min)



fIN = 4 MHz, VIN = FS − 0.25 dB 60 dBc


SFDR Spurious Free Dynamic Range fIN = 50 MHz, VIN = FS − 0.25 dB 60 dBc



fIN = 4 MHz, VIN = FS − 0.25 dB −60 dBc


THD Total Harmonic Distortion fIN = 50 MHz, VIN = FS − 0.25 dB −60 dBc

fIN = 70 MHz, VIN = FS − 0.25 dB -56 dBc




HD2 2nd Harmonic Distortion fIN = 50 MHz, VIN = FS − 0.25 dB −66 dBc





HD3 3rd Harmonic Distortion fIN = 50 MHz, VIN = FS − 0.25 dB −72 dBc



f1 = 11 MHz, VIN = FS − 6.25 dBIMD Intermodulation Distortion -55 dBcf2 = 12 MHz, VIN = FS − 6.25 dB




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ADC08200


Converter Electrical Characteristics (continued)The following specifications apply for VA = VDR = +3.0VDC, VRT = +1.9V, VRB = 0.3V, CL = 5 pF, fCLK = 200 MHz at 50% dutycycle. Boldface limits apply for TJ = TMIN to TMAX: all other limits TJ = 25°C (1)(2)(3)


POWER SUPPLY CHARACTERISTICS

DC Input 69.75 86 mA (max)IA Analog Supply Current

fIN = 10 MHz, VIN = FS − 3 dB 69.75 mA

IDR Output Driver Supply Current DC Input, PD = Low 0.25 0.6 mA (max)

DC Input, PD = Low 70 86.6 mA (max)IA + IDR Total Operating Current

CLK Low, PD = Hi 0.3 mA

DC Input, Excluding Reference 210 260 mW (max)PC Power Consumption

CLK Low, PD = Hi 1 mW

FSE change with 2.7V to 3.3V change inPSRR1 Power Supply Rejection Ratio 54 dBVA

SNR reduction with 200 mV at 1MHz onPSRR2 Power Supply Rejection Ratio 45 dBsupply

AC ELECTRICAL CHARACTERISTICS

fC1 Maximum Conversion Rate 230 200 MHz (min)

fC2 Minimum Conversion Rate 10 MHz

tCL Minimum Clock Low Time 0.87 1.0 ns (min)

tCH Minimum Clock High Time 0.65 0.75 ns (min)

CLK to Data Invalid, VA = 3.3V to 3.6V, tAOutput Hold Time, Output Falling (5) 2.4 3.3 ns (max)= −40°C to +105°C, CL = 8 pFtOH

CLK to Data Invalid, VA = 3.3V to 3.6V, tAOutput Hold Time, Output Rising (5) 1.9 2.5 ns (max)= −40°C to +105°C, CL = 8 pF

2.4 ns (min)CLK to Data Transition, VA = 3.3V toOutput Delay, Output Falling (5) 3.93.6V, VA = −40°C to +105°C, CL = 8 pF 5.1 ns (max)tOD

2.4 ns (min)CLK to Data Transition, VA = 3.3V toOutput Delay, Output Rising (5) 3.33.6V, tA = −40°C to +105°C, CL = 8 pF 4.0 ns (max)

Output Falling, VA = 3.3V, CL = 8 pF, 0.73 V/nstA = −40°C to +105°CtSLEW Output Slew Rate (6)

Output Rising, VA = 3.3V, CL = 8 pF, 0.88 V/nstA = −40°C to +105°C

Pipeline Delay (Latency) 6 Clock Cycles

tAD Sampling (Aperture) Delay CLK Rise to Acquisition of Data 2.6 ns

tAJ Aperture Jitter 2 ps rms

(5) These specifications are ensured by design and not tested.(6) Typical output slew rate is based upon the maximum tOD and tOH figures.




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ADC08200


Specification Definitions

APERTURE (SAMPLING) DELAY is that time required after the rise of the clock input for the sampling switch toopen. The Sample/Hold circuit effectively stops capturing the input signal and goes into the “hold” modetAD after the clock goes high.

APERTURE JITTER is the variation in aperture delay from sample to sample. Aperture jitter shows up as inputnoise.

CLOCK DUTY CYCLE is the ratio of the time that the clock wave form is at a logic high to the total time of oneclock period.

DIFFERENTIAL NON-LINEARITY (DNL) is the measure of the maximum deviation from the ideal step size of 1LSB. Measured at 200 Msps with a ramp input.

EFFECTIVE NUMBER OF BITS (ENOB, or EFFECTIVE BITS) is another method of specifying Signal-to-Noiseand Distortion Ratio, or SINAD. ENOB is defined as (SINAD – 1.76) / 6.02 and says that the converter isequivalent to a perfect ADC of this (ENOB) number of bits.

FULL POWER BANDWIDTH is a measure of the frequency at which the reconstructed output fundamentaldrops 3 dB below its low frequency value for a full scale input.

FULL-SCALE ERROR is a measure of how far the last code transition is from the ideal 1½ LSB below VRT and isdefined as:

Vmax + 1.5 LSB – VRT

where• Vmax is the voltage at which the transition to the maximum (full scale) code occurs (1)

INTEGRAL NON-LINEARITY (INL) is a measure of the deviation of each individual code from a line drawn fromzero scale (½ LSB below the first code transition) through positive full scale (½ LSB above the last codetransition). The deviation of any given code from this straight line is measured from the center of that codevalue. The end point test method is used. Measured at 200 Msps with a ramp input.

INTERMODULATION DISTORTION (IMD) is the creation of additional spectral components as a result of twosinusoidal frequencies being applied to the ADC input at the same time. it is defined as the ratio of thepower in the second and third order intermodulation products to the power in one of the originalfrequencies. IMD is usually expressed in dBFS.

MISSING CODES are those output codes that are skipped and will never appear at the ADC outputs. Thesecodes cannot be reached with any input value.

OUTPUT DELAY is the time delay after the rising edge of the input clock before the data update is present atthe output pins.

OUTPUT HOLD TIME is the length of time that the output data is valid after the rise of the input clock.

PIPELINE DELAY (LATENCY) is the number of clock cycles between initiation of conversion and when thatdata is presented to the output driver stage. New data is available at every clock cycle, but the data lagsthe conversion by the Pipeline Delay plus the Output Delay.

POWER SUPPLY REJECTION RATIO (PSRR) is a measure of how well the ADC rejects a change in the powersupply voltage. For the ADC08200, PSRR1 is the ratio of the change in Full-Scale Error that results from achange in the DC power supply voltage, expressed in dB. PSRR2 is a measure of how well an AC signalriding upon the power supply is rejected from the output and is here defined as

where• SNR0 is the SNR measured with no noise or signal on the supply line• SNR1 is the SNR measured with a 1 MHz, 200 mVP-P signal riding upon the supply lines (2)

SIGNAL TO NOISE RATIO (SNR) is the ratio, expressed in dB, of the rms value of the input signal at the outputto the rms value of the sum of all other spectral components below one-half the sampling frequency, notincluding harmonics or d.c.




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THD = 20 x log + . . . + AAf2

2 f10

2

Af12

ADC08200


SIGNAL TO NOISE PLUS DISTORTION (S/(N+D) or SINAD) is the ratio, expressed in dB, of the rms value ofthe input signal at the output to the rms value of all of the other spectral components below half the clockfrequency, including harmonics but excluding d.c.

SPURIOUS FREE DYNAMIC RANGE (SFDR) is the difference, expressed in dB, between the rms values of theinput signal at the output and the peak spurious signal, where a spurious signal is any signal present inthe output spectrum that is not present at the input.

TOTAL HARMONIC DISTORTION (THD) is the ratio expressed in dB, of the rms total of the first nine harmoniclevels at the output to the level of the fundamental at the output. THD is calculated as

where• Af1 is the RMS power of the fundamental (output) frequency• Af2 through Af10 are the RMS power of the first 9 harmonic frequencies in the output spectrum (3)

ZERO SCALE OFFSET ERROR is the error in the input voltage required to cause the first code transition. It isdefined as

VOFF = VZT − VRB

where• VZT is the first code transition input voltage (4)

Timing Diagram

Figure 2. ADC08200 Timing Diagram




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ADC08200


Typical Performance CharacteristicsVA = VDR = 3V, fCLK = 200 MHz, fIN = 50 MHz, unless otherwise stated

INLvs.

INL Temperature

Figure 3. Figure 4.

INL INLvs. vs.

Supply Voltage Sample Rate

Figure 5. Figure 6.

DNLvs.

DNL Temperature

Figure 7. Figure 8.




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ADC08200


Typical Performance Characteristics (continued)VA = VDR = 3V, fCLK = 200 MHz, fIN = 50 MHz, unless otherwise stated

DNL DNLvs. vs.


Figure 9. Figure 10.

SNR SNRvs. vs.

Temperature Supply Voltage


SNR SNRvs. vs.

Sample Rate Input Frequency





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ADC08200



SNR Distortionvs. vs.

Clock Duty Cycle Temperature


Distortion Distortionvs. vs.



Distortion Distortionvs. vs.

Input Frequency Clock Duty Cycle





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ADC08200



SINAD/ENOB SINAD/ENOBvs. vs.

Temperature Supply Voltage


SINAD/ENOB SINAD/ENOBvs. vs.

Sample Rate Input Frequency


SINAD/ENOB Power Consumptionvs. vs.

Clock Duty Cycle Sample Rate





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ADC08200



Spectral Response @ fIN = 50 MHz Spectral Response @ fIN = 76 MHz


Spectral Response @ fIN = 99 MHz Intermodulation Distortion





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8 11

AGND

ADC08200

D713

D614

D515

D022

D121

D220

D319

D416

6

3

+3V

110

5 17

DR GND

10

V RT

VIN

10 PF

+

220

2

VRB

24

CLK

0.1 PF

9

23PD

0.1 PF

10 PF++

1 4 180.1 PF

10 PF

DR VDVA

Choke

0.1 PF

10 PF+

12

+3V

1%

1%

0.1 PF

1.5V,nominal

7VIN GND

ADC08200


FUNCTIONAL DESCRIPTION

The ADC08200 uses a new, unique architecture that achieves over 7 effective bits at input frequencies up to andbeyond 100 MHz.

The analog input signal that is within the voltage range set by VRT and VRB is digitized to eight bits. Input voltagesbelow VRB will cause the output word to consist of all zeroes. Input voltages above VRT will cause the output wordto consist of all ones.

Incorporating a switched capacitor bandgap, the ADC08200 exhibits a power consumption that is proportional tofrequency, limiting power consumption to what is needed at the clock rate that is used. This and its excellentperformance over a wide range of clock frequencies makes it an ideal choice as a single ADC for many 8-bitneeds.

Data is acquired at the rising edge of the clock and the digital equivalent of that data is available at the digitaloutputs 6 clock cycles plus tOD later. The ADC08200 will convert as long as the clock signal is present. Theoutput coding is straight binary.

The device is in the active state when the Power Down pin (PD) is low. When the PD pin is high, the device is inthe power down mode, where the output pins hold the last conversion before the PD pin went high and thedevice consumes just 1.4 mW . Holding the clock input low will further reduce the power consumption in thepower down mode to about 1 mW.

APPLICATIONS INFORMATION

REFERENCE INPUTS

The reference inputs VRT and VRB are the top and bottom of the reference ladder, respectively. Input signalsbetween these two voltages will be digitized to 8 bits. External voltages applied to the reference input pins shouldbe within the range specified in the Operating Ratings Table. Any device used to drive the reference pins shouldbe able to source sufficient current into the VRT pin and sink sufficient current from the VRB pin to maintain thedesired voltages.

Because of the ladder and external resistor tolerances, the reference voltage of this circuit can vary too much forsome applications.

Figure 31. Simple, low component count reference biasing.




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8 11

AGND

ADC08200

D713

D614

D515

D022

D121

D220

D319

D416

6

4.7k

3

0.1 PF

309:

+3V

470:

5 17

DR GND

10

VRT

VIN

1/2 LM8272

-

+ 18

4

3

2

10 PF+

+3V

0.01 PF

1 PF

1/2 LM8272

+

-6

5

1.62k

0.01 PF

7

604:LM4040-2.5

2

0.1 PF

10 PF++

124 180.1 PF

10 PF

DR VDVA

Choke

1

VRB

24

CLK

0.1 PF

9

23PD

0.1 PF

7VIN GND

1 PF

4.7k

1 PF

ADC08200


The reference bias circuit of Figure 31 is very simple and the performance is adequate for many applications.However, circuit tolerances will lead to a wide reference voltage range. Better reference stability can be achievedby driving the reference pins with low impedance sources.

The circuit of Figure 32 will allow a more accurate setting of the reference voltages. The upper amplifier must beable to source the reference current as determined by the value of the reference resistor and the value of (VRT −VRB). The lower amplifier must be able to sink this reference current. Both amplifiers should be stable with acapacitive load. The LM8272 was chosen because of its rail-to-rail input and output capability, its high currentoutput and its ability to drive large capacitive loads.

The divider resistors at the inputs to the amplifiers could be changed to suit the application reference voltageneeds, or the divider can be replaced with potentiometers or DACs for precise settings. The bottom of the ladder(VRB) may be returned to ground if the minimum input signal excursion is 0V.

VRT should always be more positive than VRB by the minimum VRT - VRB difference in Electrical Characteristics tominimize noise. While VRT may be as high as the VA supply voltage and VRB may be as low as ground, thedifference between these two voltages (VRT − VRB) should not exceed 2.3V to prevent waveform distortion.

The VRM pin is the center of the reference ladder and should be bypassed to a quiet point in the ground planewith a 0.1 µF capacitor. DO NOT leave this pin open and DO NOT load this pin with more than 10µA.

Figure 32. Driving the reference to force desired values requires driving with a low impedance source.

THE ANALOG INPUT

The analog input of the ADC08200 is a switch followed by an integrator. The input capacitance changes with theclock level, appearing as 3 pF when the clock is low, and 4 pF when the clock is high. The sampling nature ofthe analog input causes current spikes at the input that result in voltage spikes there. Any amplifier used to drivethe analog input must be able to settle within the clock high time. The LMH6702 and the LMH6628 have beenfound to be good amplifiers to drive the ADC08200.




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22

+

-

20012

240

47100

10 pFSignal

Input

8 11

AGND

ADC08200 D713

D614

D515

D022

D121

D220

D319

D416

6

3

7

10

VRT

5

0.1 PF

10 PF+

+

124 18

0.1 PF

10 PF

DR VDVA

Choke

1

VRB

24

CLK

9

23PD

+3V

LMH6702

2

17DR GND

+5V

-5V

0.1 PF

0.1 PF

10

Gain Adjust

4.7k

1k1k

0.33 PF

+3V

*

*

Offset Adjust

*

*URXQGFRQQHFWLRQVPDUNHGZLWK³*´should enter the ground plane at a

common point

VIN

7VIN GND

VRM

ADC08200


Figure 33 shows an example of an input circuit using the LMH6702. Any input amplifier should incorporate somegain as operational amplifiers exhibit better phase margin and transient response with gains above 2 or 3 thanwith unity gain. If an overall gain of less than 3 is required, attenuate the input and operate the amplifier at ahigher gain, as shown in Figure 33.

The RC at the amplifier output filters the clock rate energy that comes out of the analog input due to the inputsampling circuit. The optimum time constant for this circuit depends not only upon the amplifier and ADC, butalso on the circuit layout and board material. A resistor value should be chosen between 18Ω and 47Ω and thecapacitor value chose according to the formula

(5)

The value of "C" in the formula above should include the ADC input capacitance when the clock is high

This will provide optimum SNR performance for Nyquist applications. Best THD performance is realized when thecapacitor and resistor values are both zero, but this would compromise SNR and SINAD performance. Generally,the capacitor should not be added for undersampling applications.

The circuit of Figure 33 has both gain and offset adjustments. If you eliminate these adjustments normal circuittolerances may result in signal clipping unless care is exercised in the worst case analysis of componenttolerances and the input signal excursion is appropriately limited to account for the worst case conditions.

Full scale and offset adjustments may also be made by adjusting VRT and VRB, perhaps with the aid of a pair ofDACs.

Figure 33. The input amplifier should incorporate some gain for best performance (see text).

POWER SUPPLY CONSIDERATIONS

A/D converters draw sufficient transient current to corrupt their own power supplies if not adequately bypassed. A10 µF tantalum or aluminum electrolytic capacitor should be placed within an inch (2.5 cm) of the A/D powerpins, with a 0.1 µF ceramic chip capacitor placed within one centimeter of the converter's power supply pins.Leadless chip capacitors are preferred because they have low lead inductance.




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ADC08200


While a single voltage source is recommended for the VA and VDR supplies of the ADC08200, these supply pinsshould be well isolated from each other to prevent any digital noise from being coupled into the analog portionsof the ADC. A choke or 27Ω resistor is recommended between these supply lines with adequate bypasscapacitors close to the supply pins.

As is the case with all high speed converters, the ADC08200 should be assumed to have little power supplyrejection. None of the supplies for the converter should be the supply that is used for other digital circuitry in anysystem with a lot of digital power being consumed. The ADC supplies should be the same supply used for otheranalog circuitry.

No pin should ever have a voltage on it that is in excess of the supply voltage or below ground by more than 300mV, not even on a transient basis. This can be a problem upon application of power and power shut-down. Besure that the supplies to circuits driving any of the input pins, analog or digital, do not come up any faster thandoes the voltage at the ADC08200 power pins.

THE DIGITAL INPUT PINS

The ADC08200 has two digital input pins: The PD pin and the Clock pin.

The PD Pin

The Power Down (PD) pin, when high, puts the ADC08200 into a low power mode where power consumption isreduced to about 1.4 mW with the clock running, or to about 1 mW with the clock held low. Output data is validand accurate about 1 microsecond after the PD pin is brought low.

The digital output pins retain the last conversion output code when either the clock is stopped or the PD pin ishigh.

The ADC08200 Clock

Although the ADC08200 is tested and its performance is ensured with a 200 MHz clock, it typically will functionwell with clock frequencies from 10 MHz to 230 MHz.

The low and high times of the clock signal can affect the performance of any A/D Converter. Because achievinga precise duty cycle is difficult, the ADC08200 is designed to maintain performance over a range of duty cycles.While it is specified and performance is ensured with a 50% clock duty cycle and 200 Msps, ADC08200performance is typically maintained with clock high and low times of 0.65 ns and 0.87 ns, respectively,corresponding to a clock duty cycle range of 13% to 82.5% with a 200 MHz clock. Note that minimum low andhigh times may not be simultaneously asserted.

The CLOCK line should be series terminated at the clock source in the characteristic impedance of that line if theclock line is longer than

where• tr is the clock rise time• tprop is the propagation rate of the signal along the trace• (6)

Typical tprop is about 150 ps/inch (59 ps/cm) on FR-4 board material.

If the clock source is used to drive more than just the ADC08200, the CLOCK pin should be a.c. terminated witha series RC to ground such that the resistor value is equal to the characteristic impedance of the clock line andthe capacitor value is

where• tPD is the signal propagation rate down the clock line• "L" is the line length• ZO is the characteristic impedance of the clock line (7)




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R

C

LMH6702

ADC ClockSource

Locate Clock Sourcenear ADC clock pin

RF

RIN

SingleGroundPlane

ADC08200

Locate power supply onthe digital side of the

ADC

Locate driving amplifiernear ADC input pin

ADC08200


This termination should be located as close as possible to, but within one centimeter of, the ADC08200 clock pin.Further, this termination should be close to but beyond the ADC08200 clock pin as seen from the clock source.Typical tprop is about 150 ps/inch on FR-4 board material. For FR-4 board material, the value of C becomes

where• L is the length of the clock line in inches (8)

This termination should be located as close as possible to, but within one centimeter of, the ADC08200 clock pin.

LAYOUT AND GROUNDING

Proper grounding and proper routing of all signals are essential to ensure accurate conversion. A combinedanalog and digital ground plane should be used.

Coupling between the typically noisy digital circuitry and the sensitive analog circuitry can lead to poorperformance that may seem impossible to isolate and remedy. The solution is to keep all lines separated fromeach other by at least six times the height above the reference plane, and to keep the analog circuitry wellseparated from the digital circuitry.

The DR GND connection to the ground plane should not use the same feedthrough used by other groundconnections.

High power digital components should not be located on or near a straight line between the ADC or any linearcomponent and the power supply area as the resulting common return current path could cause fluctuation in theanalog input “ground” return of the ADC.

Generally, analog and digital lines should cross each other at 90° to avoid getting digital noise into the analogpath. In high frequency systems, however, avoid crossing analog and digital lines altogether. Clock lines shouldbe isolated from ALL other lines, analog AND digital. Even the generally accepted 90° crossing should beavoided as even a little coupling can cause problems at high frequencies. Best performance at high frequenciesis obtained with a straight signal path.

The analog input should be isolated from noisy signal traces to avoid coupling of spurious signals into the input.Any external component (e.g., a filter capacitor) connected between the converter's input and ground should beconnected to a very clean point in the ground plane.

Figure 34. Layout Example




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ADC08200


Figure 34 gives an example of a suitable layout. All analog circuitry (input amplifiers, filters, referencecomponents, etc.) should be placed together away from any digital components.

DYNAMIC PERFORMANCE

The ADC08200 is a.c. tested and its dynamic performance is ensured. To meet the published specifications, theclock source driving the CLK input must exhibit less than 2 ps (rms) of jitter. For best a.c. performance, isolatingthe ADC clock from any digital circuitry should be done with adequate buffers, as with a clock tree. SeeFigure 35.

It is good practice to keep the ADC clock line as short as possible and to keep it well away from any othersignals. Other signals can introduce jitter into the clock signal. The clock signal can also introduce noise into theanalog path.

Figure 35. Isolating the ADC Clock from Digital Circuitry

COMMON APPLICATION PITFALLS

Driving the inputs (analog or digital) beyond the power supply rails. For proper operation, all inputs shouldnot go more than 300 mV below the ground pins or 300 mV above the supply pins. Exceeding these limits oneven a transient basis may cause faulty or erratic operation. It is not uncommon for high speed digital circuits(e.g., 74F and 74AC devices) to exhibit undershoot that goes more than a volt below ground. A 51Ω resistor inseries with the offending digital input will usually eliminate the problem.

Care should be taken not to overdrive the inputs of the ADC08200. Such practice may lead to conversioninaccuracies and even to device damage.

Attempting to drive a high capacitance digital data bus. The more capacitance the output drivers mustcharge for each conversion, the more instantaneous digital current is required from VDR and DR GND. Theselarge charging current spikes can couple into the analog section, degrading dynamic performance. Buffering thedigital data outputs (with a 74AF541, for example) may be necessary if the data bus capacitance exceeds 5 pF.Dynamic performance can also be improved by adding 47Ω to 56Ω series resistors at each digital output,reducing the energy coupled back into the converter input pins.

Using an inadequate amplifier to drive the analog input. As explained in THE ANALOG INPUT, thecapacitance seen at the input alternates between 3 pF and 4 pF with the clock. This dynamic capacitance ismore difficult to drive than is a fixed capacitance, and should be considered when choosing a driving device.

Driving the VRT pin or the VRB pin with devices that can not source or sink the current required by theladder. As mentioned in REFERENCE INPUTS, care should be taken to see that any driving devices can sourcesufficient current into the VRT pin and sink sufficient current from the VRB pin. If these pins are not driven withdevices than can handle the required current, these reference pins will not be stable, resulting in a reduction ofdynamic performance.

Using a clock source with excessive jitter, using an excessively long clock signal trace, or having othersignals coupled to the clock signal trace. This will cause the sampling interval to vary, causing excessiveoutput noise and a reduction in SNR performance. The use of simple gates with RC timing is generallyinadequate as a clock source.




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ADC08200


REVISION HISTORY

Changes from Revision L (March 2013) to Revision M Page

• Changed layout of National Data Sheet to TI format .......................................................................................................... 20




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PACKAGE OPTION ADDENDUM

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Addendum-Page 1

PACKAGING INFORMATION

Orderable Device Status(1)

Package Type PackageDrawing

Pins PackageQty

Eco Plan(2)

Lead finish/Ball material

(6)

MSL Peak Temp(3)

Op Temp (°C) Device Marking(4/5)

Samples

ADC08200CIMT ACTIVE TSSOP PW 24 61 Non-RoHS& Green

Call TI Call TI -40 to 85 ADC08200CIMT

ADC08200CIMT/NOPB ACTIVE TSSOP PW 24 61 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 ADC08200CIMT

ADC08200CIMTX/NOPB ACTIVE TSSOP PW 24 2500 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 ADC08200CIMT

(1) The marketing status values are defined as follows:ACTIVE: Product device recommended for new designs.LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.PREVIEW: Device has been announced but is not in production. Samples may or may not be available.OBSOLETE: TI has discontinued the production of the device.

(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substancedo not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI mayreference these types of products as "Pb-Free".RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide basedflame retardants must also meet the <=1000ppm threshold requirement.

(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.

(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.

(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuationof the previous line and the two combined represent the entire Device Marking for that device.

(6) Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to twolines if the finish value exceeds the maximum column width.

Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on informationprovided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken andcontinues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.

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PACKAGE OPTION ADDENDUM

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Addendum-Page 2

In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.

TAPE AND REEL INFORMATION

*All dimensions are nominal

Device PackageType

PackageDrawing

Pins SPQ ReelDiameter

(mm)

ReelWidth

W1 (mm)

A0(mm)

B0(mm)

K0(mm)

P1(mm)

W(mm)

Pin1Quadrant

ADC08200CIMTX/NOPB TSSOP PW 24 2500 330.0 16.4 6.95 8.3 1.6 8.0 16.0 Q1

PACKAGE MATERIALS INFORMATION

www.ti.com 26-Mar-2013

Pack Materials-Page 1

*All dimensions are nominal

Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)

ADC08200CIMTX/NOPB TSSOP PW 24 2500 367.0 367.0 35.0

PACKAGE MATERIALS INFORMATION

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Pack Materials-Page 2

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PACKAGE OUTLINE

C

22X 0.65

2X7.15

24X 0.300.19

TYP6.66.2

1.2 MAX

0.150.05

0.25GAGE PLANE

-80

BNOTE 4

4.54.3

A

NOTE 3

7.97.7

0.750.50

(0.15) TYP

TSSOP - 1.2 mm max heightPW0024ASMALL OUTLINE PACKAGE

4220208/A 02/2017

1

1213

24

0.1 C A B

PIN 1 INDEX AREA

SEE DETAIL A

0.1 C

NOTES: 1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing per ASME Y14.5M. 2. This drawing is subject to change without notice. 3. This dimension does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not exceed 0.15 mm per side. 4. This dimension does not include interlead flash. Interlead flash shall not exceed 0.25 mm per side.5. Reference JEDEC registration MO-153.

SEATINGPLANE

A 20DETAIL ATYPICAL

SCALE 2.000

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EXAMPLE BOARD LAYOUT

0.05 MAXALL AROUND

0.05 MINALL AROUND

24X (1.5)

24X (0.45)

22X (0.65)

(5.8)

(R0.05) TYP


4220208/A 02/2017

NOTES: (continued) 6. Publication IPC-7351 may have alternate designs. 7. Solder mask tolerances between and around signal pads can vary based on board fabrication site.

LAND PATTERN EXAMPLEEXPOSED METAL SHOWN

SCALE: 10X

SYMM

SYMM

1

12 13

24

15.000

METALSOLDER MASKOPENING

METAL UNDERSOLDER MASK

SOLDER MASKOPENING

EXPOSED METALEXPOSED METAL

SOLDER MASK DETAILS

NON-SOLDER MASKDEFINED

(PREFERRED)

SOLDER MASKDEFINED

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EXAMPLE STENCIL DESIGN

24X (1.5)

24X (0.45)

22X (0.65)

(5.8)

(R0.05) TYP


4220208/A 02/2017

NOTES: (continued) 8. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate design recommendations. 9. Board assembly site may have different recommendations for stencil design.

SOLDER PASTE EXAMPLEBASED ON 0.125 mm THICK STENCIL

SCALE: 10X

SYMM

SYMM

1

12 13

24

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Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265Copyright © 2021, Texas Instruments Incorporated

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adc08200 8-bit,20 msps to 200 msps, low power a/d ...just 1.05 mw per mhz of clock frequency, or 210...

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